Circuit interrupter



Dec. 1,` 1942.

H. J. CRABBS CIRCUIT INTERRUPTER Fil'ed Sept. 9, 1959 l vl.'

INVENToR .71m a. n.` l wfro Jim j` wma 6 W Patented Dec. 1, 1942 CIRCUITINTERRUPTER Herbert J. Crabbs, Wilkinsburg,"Pa., assignor toWestinghouse Electric & Manufacturing vC'ompany, East PittsburPennsylvania.

gh, Pa., a corporationl of.V

Application SeptemberlS, 1939, Serial No. 294,074 y (Cl. 200-162) 8Claims.

My invention relates, generally, to circuit interrupters, and isparticularly embodied in disconnecting switches.

My invention is especially adapted for split blade disconnectingswitches, and it is a primary object of my invention to provide new andimproved means in conjunction with such switches, for insuring at alltimes adequate contact pressure on the separable contacting portions ofthese switches, while providing for proper alignment of the blade andits break tongue.

Itis a well known fact that practically all known conductors and contactmediums will corrode under adverse atmospheric conditions. One metalwill build up a thicker layer of corrosion under a given inuence thananother, although the thicker layer may produce the lower contact drop,depending on the conducting qualities of the corrosion layer. Allcorrosions to some degree tend to increase contact drop and, therefore,increase heating of the contact which, in turn, accelerates corrosion.

High contact pressure over a reduced area tends to maintain ametal-to-metal contact and reduce corrosion at the contact surface.Lower contact pressures reduce wear on the contact surfaces caused byopening and closing of switches and tends to avoid galling of metals,which sometimes results when too high wiping pressures are used.

It, therefore, would appear that the ideal wiping contact would be oneon which a moderately heavy contact pressure is normal, which pressurewould, under average atmospheric conditions, result in a contact dropthat would not cause abnormal heating of the switch contacts but whichunder abnormal atmospheric conditions and resultant heating wouldautomatically increase the pressure between contacts, resulting in highpressure metal areas tending to pierce the corrosion and again lower thecontact drop and temperature, and retard the acceleration of corrosion.l

It is therefore, an object oi my invention to provide contact pressuremeans which is automatically responsive to the contact temperature toincrease the pressure with a rise in contacttemperature.

It is a further object of my invention to provide bimetallic pressuremeans for the contacting portions of a switch, to very the pressure onsuch portions in accordance with their temperature.V

It is well known that in the assembly of dis- I connecting switches,especially where the hinge l and break tongues of a switch areindependently mounted ona support, that it is often impossible to easilyobtain perfect alignment of the break tongue with the plane of closingmovement ofv the blade.

Another object of my invention, therefore, isv to provide a novel formof disconnecting switch, parts of which are relatively movably mountedto properly align the blade and break tongue parts.

A further object of my invention is to provide a switch blade having auniversal mounting to insure proper alignment of the blade and itsassociated break tongue.

These and other objects of my invention will become more apparent whenconsidered in connection with the following detailed description and theattached drawing, which discloses preferred embodiments of my invention:

In the drawing:

Figure 1 is a plan view of a disconnecting switch showing one form ofswitch in whichmy invention may be embodied; v

Fig. 2 is a side View of the switch shown in Fig. 1;

Fig. 3 is an enlarged cross-sectional view through the hinge tongue ofthe switch shown in Figs. 1 and 2; Y

Fig. 4 is a cross-sectional view similar to Fig.

3, but showing a modied hinge'construction; y

and

Fig. 5 is a partial side view of a modied break end construction for adisconnecting switch.

I'Referring to Figs. 1 and 2, I have shown a pair of insulating supportmembers 2 and 4, having flanged apertured ba'ses secured to the'supporting base 6, as by the machine screws 8. The insulators 2 and 4may be of any desired'insulating material, such for example, asporcelain or the like. The insulator 2 supports a hinge tongue I0 havinga laterally extending terminal portion I2, and the insulator 4 supportsa break tongue I4 having a laterally eX- tending terminal portion I 6. Asplit switch blade structure I8, which includes the spaced side portions20 and 22, is pivotally secured tothe hinge tongue I0, as by means ofthe bolt 24 passing through the sides 20 and 22 of the blade I8 andthrough an aperture in the hinge tongue I0. 'Ihe bolt is secured in thissides of the split blade I8 are also secured to--A position by a nut 26'v and a locking nut 28. The opposite ends of the"V the break tongue I4to provide for movement of the blade I8 into and out of engagement withthe break tongue I4, pivoting about the bolt 24 as an axis.

The hinge tongue I is provided with annular flat inserts 30 which areadapted to be contacted by annular inserts 32 secured in the inner sidesof the sides and 22 of the split blade I8. The inserts 32 have theirouter faces convex in form to provide substantially a line contactbetween the blade I8 and the hinge tongue I0. The inserts and 32preferably have at least the surface thereof of some noble metal, suchas silver. The inserts may be of solid silver or may be of bimetallicconstruction, such as a base of copper or the like, having a silvercoating. Obviously, similar inserts or straight strip inserts may beprovided at the break end of the switch. Secured between the sides ofthe split blade I8 at a point adjacent to but spaced from the hinge endof the blade isan operating lever 36 which is rigidly secured toA theblade in any suitable manner, such for example, as by riveting or thelike. The operating lever 36 is provided with an aperture 38 in itsouter end for connection to switch operating mechanism,` or for thereception of a hook stick operating member.

At each end of the blade between the outer sides of the blade and thehead of bolts 24 and nuts 26, respectively, I have provided generallycup-shaped resilient washer elements 46. These washer elements 40 are oflaminated or a bimetallic construction comprising the outer metallicwasher element 42 of any desired material having a relatively highcoefficient of expansion, such for examples, .as brass, and an innerlayer 44 of any suitable material having a relatively7 lower coefficientof expansion, such for example, as steel. The laminations 42 and 44 aresecured together in any desired manner, such forexample as by welding.Between the bolt 24 and the hinge tongue andblade, I have provided abearing sleeve 46 over the bolt.

In the operation of this form of my invention, the bimetallic washers40, upon assembly of the device, are given an initial tension ordeflection by drawing up the nut 26 to give the desired pressure. Uponthe occurrence of abnormal atmospheric conditions, orA upon the buildingup of corrosion on the contacts due to any cause whate ever, an amountsufficient to produce a voltage d rop across the contacts suflicient tocause heating of the blade I8, the bimetallic washers-,will act toincrease their convexities, thereby pressing the sides 20 and 22 of theblade I8 together with a greater force. This action will tend to breakthrough the corrosion and provide a better contact between the blade andhinge tongue, and thus reduce the voltage drop across these parts, thisresulting in decrease of the heating effect.

In Fig. 4, I have shown a slightly modified construction of the hingedend of a disconnecting switch. The hinge tongue 48 in this form of myinvention includes an outer enlarged head portion 56 having itsperipheral edge surface 52 in the form of a segment of a, sphere. Thesides 54 and 56 of the blade of this construction embody annular convexcontacting portions 58, extending inwardly from the central bladeportion 59. The

portions 58 engage the spherical surface 52 of the hinge tongue, thusproviding a universal connection for the hinge end of the blade. Theblade contact portions 58, and the tongue contact surface 52, may beprovided with contact inserts like the inserts 30 and 32y shown in Fig'.3,

if desired. As in the previous embodiment, the blades are maintained inengagement with the hinge tongue by a bolt 60 which passes throughapertures in the sides 54 and 56 of the blade, and through an aperturein the hinge tongue 50, and is secured in position by the nut 62 and alock nut 64. Between the head of the bolt 60 and the nut 62 and theiradjacent sides of the blade, there is also provided here the bimetallicwashers 40 which function to maintain the convex contacting portions 58on the blade sides in engagement with the spherical portion 52 of thehinge tongue. The bimetallic washers 40 are identical with thosedescribed in connection with the embodiment shown in Figs. l to 3, andfunction in the same manner in response to heating of the blade as wasdescribed in connection with the previous embodiment.

A bearing sleeve 66 is interposed between the bolt 60 and the sides ofthe switch blade and the-head portion 50 of the hinge tongue. Thisbearing sleeve 66 snugly ts the bolt 60 and the apertures in blade sides54 and 56, andis loosely mounted in the head portion 50 to allow for-limited movement of the switch blade relative to the hinge tongue inall directions, except the direction of movement toward and awayl fromthe break tongue, in which direction of movement the blade is free tomove," a relatively great amount, up to if desired. ,f The relativemovef ment of the blade andj hinge tongue in all other directions may belimited, either by vthe clearance betweenthe hinge tongue and vthebearing sleeve 66, or by the clearance between the blade sides and theenlarged portion 5II of thefhrigetongue;

or by the clearance between lthe lower edges of the blade sides and thelower` portion 48 of the hinge tongue. These; clearances can beregulated so as to keep the blade sides in reasonable Alongitudinalalignment with respect to each otherV and their associated breaktongue.v

In the operation of this-embodiment of my'invention, it is well knownthat it is often impossible to easily alignaswitch blade and itsassociated break tongue,especiallywhere the two are mountedindependently ,ony a-support. However, with the hinge construction shownin Fig.- 4, it is obvious that any slight disalignment of the switchblade and its break tongue is easily compensated for by a slight lateralmovement ofthe blade relative tothe hinge tongue in any ,desireddirection, inasmuchxasfthishinge construction is, in effect, auniversal. mounting, to give perfect alignment of the switch blade andbreak tongue.

This is a very desirable feature because it pro-` motes more even wearon -thecontacting portions of the blade, andA hinge and break tongues,and

also relieves-the switch `blade and tongues fromV any torsional orlateral stresses, thus insuring a more efcient switchoperation and alonger switching life. f

In Fig. 5, I have shown Aa modification of the break end of adisconnecting switch. whichswitch is generally of the same type as--thatShown in 'Figs 1 and 2. The modified structure inithis embodiment of myinvention Vrelates to the bimetallic construction, Insteadl of usingbimetal-l lic washers for pressing the blade sides into engagement withthe break tongue, bimetallic strips I2 have their ends bolted to theVouter. sides :of a split switch blade Iilibyv the bolts "IIIl whichalsol act to maintain the blades against separation...

The bimetallic strips 'I2 in this instance, however, have the innerlaminations thereof of a material .fhaving a relatively-highcoeflicient:of expansiontongue '14. In other words, with an increase in temperature,the bimetallic strips-12 will tend to assume an outwardly concave form.This construction also enables the use of a solid breaks-f,

tongue '14, inasmuch as the blade bolts 10 are placed at opposite sidesof the break tongue and do not need to pass through the tongue.

It is obvious that I have provided a disconnecting switch blade with apressure means for both the break and hinge ends of the blade, whichpressure means is responsive to rises in temperature to exert a greaterpressure on the contacting portions of the blade and tongue, to tend tobreak down any corrosion on such contacting portions to provide a bettercontact, and reduce the voltage drop caused by the corrosion, and`hencebring down the temperature of the parts. This heat responsive pressuremeans is obviously adapted for use with any desired type ofdisconnecting switch. I have shown it applied to two types of hingeconstructions in Figs. 3 and 4, and to two diierent types of breakconstructions shown in Figs. 1, 2 and 5.

It is also obvious that, in conjunction with the above structure, I haveprovided a novel hinge construction for a disconnecting switch bladewhich is, in effect, a ball and socket joint, or a universal joint,permitting movement of the blade in the usual manner into and out ofengagement with its associated break tongue, and also permitting alimited movement of the blade in all other directions to providesubstantially perfect alignment of the blade with its break tongue, thusrelieving the parts of any undue strain caused by disalignment andinsuring even contact pressure of the blade on the tongues.

Having described preferred embodiments of my invention in accordancewith the patent statutes, I wish it to be understood that my inventionshall be interpreted as broadly as possible and not limited to thespecic embodiments herein disclosed, inasmuch as it will be obvious,particularly to persons skilled in the art, that many changes andmodifications could bef-made in, the structures disclosed withoutdeparting frbmfthe broad spirit and scope of my invention;-

For example, it is obvious that the universal mounting constructionshown in Fig. 4 could be used with the ordinary type of resilientcupshaped washer instead of my bimetallic washers, as shown. Likewise,my invention is equally applicable to a switch construction employingsplit tongues and a single blade construction receivable between thetongues. This would constitute a mere reversal of parts, and the washerelements in such a case would be applied to the sides of the splittongue construction, rather than to the sides of the split blade, asshown on the attached drawing` Therefore, I desire that my invention begiven sibroad an interpretation as possible, and that it beilimited onlyby what is expressly set forth in th-'following claims.

I claim as my invention:

1. In arswitch, a pair of contact members, one of. said membersembodying spaced sides between which `are/received a portion of theother member, a pivot pin loosely pivotally connecting saidmernbersabout a transverse axis, and cooperatin'ggmeans on said members adaptedto be maintained in electrical contact irrespective of the retivemovements of said members in any directio` a SWtCh a pair of contactmembers loosely pivotally" 'connected about a transverse axis by a pivotpin, and cooperating means on said members adapted to bemaintainedjncon.- tact irrespective of th'e relative movements of saidmembers in any direction.

3. A pair of switch membersmovably connected by a universal joint, andmeans extending through said members for limiting said movement inalateral direction. g2

4. In a switch, a, Contact member having. a. projection with a sphericalperiphery, a second contact member having a part engaging saidperiphery, and means extending loosely through said members for holdingsaid contact members together for relative limited universal movement,including heat responsive pressure means for maintaining said part ingood electricahcontact with said periphery.

5. In a switch, a switch member having an\end in substantially th'e formof a segment or a stantially circular contacting portion of lessdisphere, a second switch member having a sub\ ameter than-saidspherical portion engaging the surface of said segment, and meansmaintaining said parts inengagement.

6. In a switch, a switch member having anV end in substantially the formof a segment of a sphere, a second switch member having spaced opposedsubstantially circular contacting portions of less diameter than saidspherical portion engaging the surface of said segment, and meansmaintaining said parts in engagement.

7. In a switch, a. pair 0f contacts, one of which is movable into andout of engagement with th'e other, thermally responsive means for urgingthe contacting portions of said contacts in engagement, said meansmounted on one of said contacts and secured thereto at points onopposite sides of the center of the engaging area of said contacts, andsaid means comprising a laminated bimeta/llic member with the laminationthereof having the greater coemcient of expansion located adjacent saidone contact.

8. A pair of switch members movably connected by a universal joint, oneof the parts of said joint including a curved engaging surface fixedwith respect to one of said members, the other part of said joint beingxed with respect to the other of said members and configurated so as tomake substantially line contact with said first-mentioned part, andmeans holding said contact members together for relative limiteduniversal movement.

HERBERT J. CRABBS.

